Lip Synch: Can somebody explain.....

Post by (PeteCresswell)
... why lip synchronization is still a problem with digital TV?

I'd say:

1) Multipath. Audio stream is on a different path than video.
2) Incompetence. Whatever must be done to compensate for the delay isn't
being done.

Does this happen for OTA broadcasting? I'm in a fringe area and have
only cable.

In addition, the path thru my TV adds 100msec delay to the headphone
out. You can get rid of that by using the RCA on the cable box.

Post by (PeteCresswell)
OK... I think I understand that voice and video are separate "Files"
so-to-speak... But what's the problem with getting them in sync at the
studio instead of my having to fiddle with my TV and still not get it
quite right?
I don't doubt there's a problem.... just wondering what it is....

--
Les Cargill

Gene E. Bloch

2014-12-24 18:48:51 UTC

Post by (PeteCresswell)
... why lip synchronization is still a problem with digital TV?

1) Multipath. Audio stream is on a different path than video.
2) Incompetence. Whatever must be done to compensate for the delay isn't
being done.

Not so. There is one stream of digital data, with the audio and video
interleaved by a standard scheme.

The software sets them up and plays them appropriately, as long as they
are correctly encoded.

Post by Les Cargill
Does this happen for OTA broadcasting? I'm in a fringe area and have
only cable.

See above.

Post by Les Cargill
In addition, the path thru my TV adds 100msec delay to the headphone
out. You can get rid of that by using the RCA on the cable box.

Now I have to check mine out to see what my set does... I always use the
RCA from the cable box, so I wouldn't have noticed the above.

--
Gene E. Bloch (Stumbling Bloch)

Les Cargill

2014-12-24 20:21:50 UTC

Post by (PeteCresswell)
... why lip synchronization is still a problem with digital TV?

1) Multipath. Audio stream is on a different path than video.
2) Incompetence. Whatever must be done to compensate for the delay isn't
being done.

Not so. There is one stream of digital data, with the audio and video
interleaved by a standard scheme.

Ideally, I'd agree.

It's possible for one stream to be on more than one path unless
you specifically design a bespoke network to avoid this.

I've seen cable channels where sync would stay "off" for say,
a half hour ( with commercials showing the "same" sync issues as
program material ), then clear up after a while. Unfortunately,
there's no way to know if that was the cable network or the original
video "file".

Post by Gene E. Bloch
The software sets them up and plays them appropriately, as long as they
are correctly encoded.

I find it hard to believe that encoding would cause this, but I've
not done a great deal of transcoding of audio/video. You'd think the
software to do that would get it right or be all but unuseable.

<Googles>

Good grief - it looks like you're right. That's pathetic.

http://www.any-video-converter.com/support/faqs/av-faqs.php

"2)You can also click Edit > Options > Video, and you will find
"Default sync factor" control bar. It's a factor to reach
synchronization. The bigger value you move to, the better accuracy of
sync you will get, meanwhile, the encoding duration will also become
longer. (Only for Any DVD Converter)"

I stand corrected.

Post by Les Cargill
Does this happen for OTA broadcasting? I'm in a fringe area and have
only cable.

See above.

Post by Les Cargill
In addition, the path thru my TV adds 100msec delay to the headphone
out. You can get rid of that by using the RCA on the cable box.

Now I have to check mine out to see what my set does... I always use the
RCA from the cable box, so I wouldn't have noticed the above.

I know I was surprised.

--
Les Cargill

UCLAN

2014-12-24 06:09:14 UTC

Post by (PeteCresswell)
... why lip synchronization is still a problem with digital TV?
OK... I think I understand that voice and video are separate "Files"
so-to-speak... But what's the problem with getting them in sync at the
studio instead of my having to fiddle with my TV and still not get it
quite right?
I don't doubt there's a problem.... just wondering what it is....

Gee, I've had my Sony Bravia for 7 years, and only had an audio/video sync
problem ONCE, and it was a problem at the NBC Nightly News studio, and they
corrected it in 15 minutes. I didn't know it was still a problem.

Patty Winter

2014-12-24 07:14:52 UTC

Post by UCLAN
Gee, I've had my Sony Bravia for 7 years, and only had an audio/video sync
problem ONCE, and it was a problem at the NBC Nightly News studio, and they
corrected it in 15 minutes. I didn't know it was still a problem.

I don't recall ever having seen the problem with OTA TV. Nor did I
realize that there were settings one could "fiddle with" to change
the relationship between the audo and video.

Patty

Bill Gill

2014-12-24 14:05:50 UTC

Post by Patty Winter

I don't recall ever having seen the problem with OTA TV. Nor did I
realize that there were settings one could "fiddle with" to change
the relationship between the audo and video.
Patty

That varies. I have a sound bar. It has several different
inputs. One of them is so that you can feed the HDMI through
the bar and it strips off the sound before it goes to the TV.
But you then have a delay which has to be compensated. There
is an adjustment that can be used to delay the sound to match
the video.

Over all I don't see too much of a problem, although a
lip synch problem does show up now and then.

Bill

Les Cargill

2014-12-24 18:34:45 UTC

Post by Patty Winter

I don't recall ever having seen the problem with OTA TV. Nor did I
realize that there were settings one could "fiddle with" to change
the relationship between the audo and video.
Patty

At home, there's very little to be done. The cable operators and
possibly the TV station operators may be able to do something
about it.

--
Les Cargill

Patty Winter

2014-12-24 20:29:55 UTC

Post by Patty Winter
I don't recall ever having seen the problem with OTA TV. Nor did I
realize that there were settings one could "fiddle with" to change
the relationship between the audo and video.

At home, there's very little to be done. The cable operators and
possibly the TV station operators may be able to do something
about it.

I had deleted the second-level quote in my reply, but it was this:
"But what's the problem with getting them in sync at the studio instead
of my having to fiddle with my TV and still not get it quite right?"

So apparently someone has some way of adjusting settings on the TV.

Patty

(PeteCresswell)

2014-12-25 01:51:38 UTC

Post by Patty Winter
"But what's the problem with getting them in sync at the studio instead
of my having to fiddle with my TV and still not get it quite right?"
So apparently someone has some way of adjusting settings on the TV.

Both my new Samsung and old Vizio have options for adjusting lip synch.

Sometimes they help, other times they do not.

--
Pete Cresswell

John McWilliams

2015-03-18 21:23:16 UTC

Post by (PeteCresswell)

Both my new Samsung and old Vizio have options for adjusting lip synch.
Sometimes they help, other times they do not.

Pretty much all AVRs and many soundbars have options for adding delay to
the sound.
Rarely will the delay be inherent in signal from the provider.
Some TVs may also have adjustments to the sound delay.

(PeteCresswell)

2014-12-24 22:32:21 UTC

I have the issue, somebody in another area watching other channels does
not... What is different? That seems to bring us back to Les Cargill's
"Incompetence" at the transmission end.

I would suspect user RCI... except that sometimes I see lip synch issues
and other times I do not... and nothing on my end is being changed.

I'm totally OTA.

Another thing I notice frequently (which would seem to point to
competence at the transmission end too) is old images whose aspect
ratios have not been adjusted to look right on 16:9 screens.

--
Pete Cresswell

Gene E. Bloch

2014-12-25 01:38:57 UTC

Post by (PeteCresswell)
Another thing I notice frequently (which would seem to point to
competence at the transmission end too) is old images whose aspect
ratios have not been adjusted to look right on 16:9 screens.

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).

It drives me nuts, truth to tell...

--
Gene E. Bloch (Stumbling Bloch)

(PeteCresswell)

2014-12-25 02:04:52 UTC

Post by Gene E. Bloch
Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

When I see stuff like that, and stuff like one of the highly-paid pretty
faces referring to a dual-rotor Chinook helicopter as "A Huey" I am
reminded of the "Nixon's The One" re-enactments of Nixon tapes where
Nixon and Oral Roberts agree that they are talking to 12-year-old minds.

viz:

beginning at 09:00

--
Pete Cresswell

John McWilliams

2014-12-25 03:48:03 UTC

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

On a proper HD TV with proper feed, there's no problem at all with the
above. True for SF Bay Area and Sacramento.

Stephen H. Fischer

2014-12-25 04:26:17 UTC

I captured "The Streets of San Francisco" 2014 Dec 21 at 16:00 Sunday on
KOFY 20.2 and Resolution was 1280 x 720.

That's 16:9 not 4:3. I think the date first shown was in 1974 when 16:9 was
non-existent.

That's the first time I have seen ME-TV messed up.

Checking at ~ 2 AM it was back to normal. And I posted the TSReader for ~ 7
PM

Yes there are problems for OTA SF Bay Area at times, some very long running
problems.

http://www.avsforum.com/forum/45-local-hdtv-info-reception/369015-san-francisco-ca-ota-post30147962.html

SHF

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

On a proper HD TV with proper feed, there's no problem at all with the
above. True for SF Bay Area and Sacramento.

Gene E. Bloch

2014-12-25 04:45:38 UTC

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

On a proper HD TV with proper feed, there's no problem at all with the
above. True for SF Bay Area and Sacramento.

The point is the feed is *not* proper.

Aside from broadcasting cell-phone videos, where no rules apply, the
news especially often sends videos that are expanded or compressed
horizontally, but properly embedded in the 1920x1080 or 1280x720 frame.

They usually broadcast decorative grey side bars to frame the distorted
images.

There is no adjustment for my (proper, as it happens) HD TV which can
fix that automatically...

--
Gene E. Bloch (Stumbling Bloch)

John McWilliams

2014-12-28 16:46:12 UTC

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

On a proper HD TV with proper feed, there's no problem at all with the
above. True for SF Bay Area and Sacramento.

The point is the feed is *not* proper.
Aside from broadcasting cell-phone videos, where no rules apply, the
news especially often sends videos that are expanded or compressed
horizontally, but properly embedded in the 1920x1080 or 1280x720 frame.
They usually broadcast decorative grey side bars to frame the distorted
images.
There is no adjustment for my (proper, as it happens) HD TV which can
fix that automatically...

Crikey, not talking about clips they show. The general feeds are fine.
Yes, an exception here or there, but it's not endemic.

Gene E. Bloch

2014-12-28 23:19:56 UTC

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

On a proper HD TV with proper feed, there's no problem at all with the
above. True for SF Bay Area and Sacramento.

The point is the feed is *not* proper.
Aside from broadcasting cell-phone videos, where no rules apply, the
news especially often sends videos that are expanded or compressed
horizontally, but properly embedded in the 1920x1080 or 1280x720 frame.
They usually broadcast decorative grey side bars to frame the distorted
images.
There is no adjustment for my (proper, as it happens) HD TV which can
fix that automatically...

Crikey, not talking about clips they show. The general feeds are fine.
Yes, an exception here or there, but it's not endemic.

OK, then, what were *you* talking about?

Oh, never mind...

--
Gene E. Bloch (Stumbling Bloch)

John McWilliams

2014-12-29 21:07:25 UTC

Lots of skinny people and lots of fat people on, say, the evening news
here (San Francisco Bay Area).
It drives me nuts, truth to tell...

On a proper HD TV with proper feed, there's no problem at all with the
above. True for SF Bay Area and Sacramento.

The point is the feed is *not* proper.
Aside from broadcasting cell-phone videos, where no rules apply, the
news especially often sends videos that are expanded or compressed
horizontally, but properly embedded in the 1920x1080 or 1280x720 frame.
They usually broadcast decorative grey side bars to frame the distorted
images.
There is no adjustment for my (proper, as it happens) HD TV which can
fix that automatically...

Crikey, not talking about clips they show. The general feeds are fine.
Yes, an exception here or there, but it's not endemic.

OK, then, what were *you* talking about?
Oh, never mind...

That, for most people in the Bay Area, it's not endemic. Therefor, not
"lots".

Jan B

2014-12-25 16:23:13 UTC

The main use for an audio delay function in the user equipment is when
splitting the audio and video to e.g a surround amplifier and a TV set
that process the image over several picture frames. The delay is
typically needed when the TV applies motion intepolation (to a higher
frame rate than the source material). This creates longer delays for
image processing so the audio needs extra delay to compensate.

I assume the production (or broadcast) chain has similar difficulties
when processing picture and sound separately.
In that case, a delayed audio can also be compensated within the range
of reducing the delay at the user setup.

RickMerrill

2015-01-02 18:43:33 UTC

Post by Jan B

The main use for an audio delay function in the user equipment is when
splitting the audio and video to e.g a surround amplifier and a TV set
that process the image over several picture frames. The delay is
typically needed when the TV applies motion intepolation (to a higher
frame rate than the source material). This creates longer delays for
image processing so the audio needs extra delay to compensate.
I assume the production (or broadcast) chain has similar difficulties
when processing picture and sound separately.
In that case, a delayed audio can also be compensated within the range
of reducing the delay at the user setup.

I have seen what should be called "audio sync" on every major TV station.
The problem arises at the studio when the audio path is shorter in time
than the video path (conversions of all kinds take place). Thus the
problem can come and go depending on the source material.

In other words the sound arrives BEFORE the relevant video. This is the
opposite of seeing a speed boat hit the water then you hear the "smack."

Call the station and tell them you noticed.

meagain

2015-03-05 00:02:10 UTC

There are two places where the dual-path occurs: at the station and at your tv.
Some tv have a way to adjust because some users route audio through their stereo.

In spite of using digital data there are still problems, even with OTA.

past examples from CNN:
station produces digital HD and SD and fail to adjust both correctly.
station merges SD or SKYPE data into digital HD stream - wrongly.
If you see audio sync problems, try to contact the station and let them know.

Sofa Slug

2015-03-19 14:29:44 UTC